Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

BACKGROUND

Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres.

METHODS

This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low-middle-income countries.

RESULTS

In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of 'single-use' consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low-middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia.

CONCLUSION

This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high- and low-middle-income countries.

Outcomes of Descemet's membrane endothelial keratoplasty performed in combination with, before, or after cataract surgery in Fuchs' endothelial dystrophy: A review of the literature and meta-analysis

This review aimed to compare the outcomes of Descemet's membrane endothelial keratoplasty (DMEK) in combination with (category 1), before (category 2), or after cataract surgery (category 3) in patients with Fuchs' endothelial dystrophy (FED). Primary outcome was gain in best-corrected log of minimum angle of resolution (logMAR) visual acuity (BCVA). Secondary outcomes were graft detachment, rebubbling rates, rejection, failure, and endothelial cell loss (ECL). In category 1, 2, and 3, 12 studies (N = 1932) were included (five in category 1 [n = 696], one in category 2 [n = 286], and two in category 3 [n = 950], and the remaining four compared between two of the three categories). At 6 months, the gain in BCVA was 0.34 ± 0.04, 0.25 ± 0.03, and 0.38 ± 0.03 logMAR in category 1, 2, and 3, respectively. The difference was significant between categories 1 and 2 (Chi² = 11.47, P < 0.01) and categories 2 and 3 (Chi² = 35.53, P < 0.01). At 12 months, the gain in BCVA was 0.52 ± 0.05 and 0.38 ± 0.06 logMAR in categories 1 & 3 (Chi² = 14.04, P < 0.01). The rebubbling rates were 15%, 4%, and 10% (P < 0.01) and the graft detachment rates were 31%, 8%, and 13% (P < 0.01) in categories 1, 2, and 3, respectively. However, graft rejection, survival rates, and ECL at 12 months were not different between categories 1 and 3. There is low certainty evidence that gain in BCVA in category 1 was comparable to category 3 at 6 months; however, it was significantly better with category 3 at 12 months. Although rebubbling and graft detachment rates were highest in category 1, there was no significant difference in graft rejection, survival rates, and ECL. Further high-quality studies are likely to change the effect estimate and have an impact on the confidence of the estimate.

Topical antibiotics for treating bacterial keratitis: a network meta‐analysis

This is a protocol for a Cochrane Review (prototype). The objectives are as follows:

To compare the effectiveness and safety of topical antibiotics for treating BK and to rank different interventions through a systematic review and NMA.

Optical aberrations following implantation of multifocal intraocular lenses: a systematic review and meta-analysis protocol

INTRODUCTION

Multifocal intraocular lens (IOLs) are used to restore vision at different focal distances. The technology of multifocal IOLs is continually advancing. Optical aberrations a property of lenses that causes spreading of light over a region resulting in a blurred or distorted image. This study aims to systematically review investigator measured and patient reported optical aberrations following implantation of multifocal IOLs during phacoemulsification surgery to treat presbyopia in adults.

METHODS AND ANALYSIS

We will conduct an electronic database search for randomised controlled trials, prospective non-randomised studies, observational studies in Ovid MEDLINE, Ovid EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, Scopus and ClinicalTrials.gov in March 2021. Eligibility criteria will include quantitative articles written in English and containing data on optical aberrations. Two independent reviewers will screen titles and abstracts and extract data from full texts, reporting outcomes according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Data extraction of key characteristics will be completed using customised forms. Methodological quality will be assessed using Cochrane Handbook 6.2.

ETHICS AND DISSEMINATION

Ethics approval is not required for this review, as it will only include published data. Findings will be published in a peer-reviewed journal and disseminated across ophthalmic networks. We anticipate that the findings of this work will be of interest to multiple stakeholders: people who have undergone cataract surgery, eye health professionals, ophthalmic surgeons, device manufacturers and policy-makers. It will also inform researchers to where there are gaps in evidence and identify areas for future research.

PROSPERO REGISTRATION NUMBER

CRD42021271050.

Corneal endothelial cell density loss following glaucoma surgery alone or in combination with cataract surgery: a systematic review protocol

OBJECTIVE

We aim to systematically assess and compare corneal endothelial cell density (ECD) loss in patients with glaucoma following glaucoma surgery and cataract surgery.

INTRODUCTION

Corneal ECD loss may occur due to intraoperative surgical trauma in glaucoma surgery or postoperatively with chronic endothelial cell trauma or irritation. Corneal oedema and decompensation after aqueous shunt glaucoma surgery has been reported but the long-term ECD loss is still unknown.

INCLUSION CRITERIA

Trabeculectomy, glaucoma filtration surgery or microinvasive glaucoma surgery in adults with ocular hypertension, primary and secondary open angle glaucoma, normal tension glaucoma and angle-closure glaucoma. Participants with pre-existing corneal disease will be excluded. Glaucoma laser treatments and peripheral iridotomy will be excluded. The outcomes include preoperative and postoperative corneal ECD, percentage change of corneal ECD and adverse events.

METHODS

We will conduct an electronic database search for randomised controlled trials, prospective non-randomised studies, observational studies in MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov and The International Prospective Register of Systematic Reviews (PROSPERO). Eligibility criteria will include quantitative articles published after and including the year 2000, written in English and containing data on ECD loss. Two independent reviewers will screen titles and abstracts and extract data from full texts, reporting outcomes according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Data extraction of key characteristics will be completed using customised forms. Methodological quality will be assessed using the Joanna Briggs Institute critical appraisal forms.

ETHICS AND DISSEMINATION

Ethics approval is not required for this review, as it will only include published data. Findings will be published in a peer-reviewed journal and disseminated across ophthalmic networks.

PROSPERO REGISTRATION NUMBER

PROSPERO CRD42020192303.

Amniotic membrane transplantation for infectious keratitis: a systematic review and meta-analysis

Infectious keratitis (IK) is the 5th leading cause of blindness globally. Broad-spectrum topical antimicrobial treatment is the current mainstay of treatment for IK, though adjuvant treatment or surgeries are often required in refractory cases of IK. This systematic review aimed to examine the effectiveness and safety of adjuvant amniotic membrane transplantation (AMT) for treating IK. Electronic databases, including MEDLINE, EMBASE and Cochrane Central, were searched for relevant articles. All clinical studies, including randomized controlled trials (RCTs), non-randomized controlled studies and case series (n > 5), were included. Primary outcome measure was time to complete corneal healing and secondary outcome measures included corrected-distance-visual-acuity (CDVA), uncorrected-distance-visual-acuity (UDVA), corneal vascularization and adverse events. A total of twenty-eight studies (including four RCTs) with 861 eyes were included. When compared to standard antimicrobial treatment alone, adjuvant AMT resulted in shorter mean time to complete corneal healing (− 4.08 days; 95% CI − 6.27 to − 1.88; p < 0.001) and better UDVA (− 0.26 logMAR; − 0.50 to − 0.02; p = 0.04) at 1 month follow-up in moderate-to-severe bacterial and fungal keratitis, with no significant difference in the risk of adverse events (risk ratio 0.80; 0.46–1.38; p = 0.42). One RCT demonstrated that adjuvant AMT resulted in better CDVA and less corneal vascularization at 6 months follow-up (both p < 0.001). None of the RCTs examined the use of adjuvant AMT in herpetic or Acanthamoeba keratitis, though the benefit was supported by a number of case series. In conclusion, AMT serves as a useful adjuvant therapy in improving corneal healing and visual outcome in bacterial and fungal keratitis (low-quality evidence). Further adequately powered, high-quality RCTs are required to ascertain its therapeutic potential, particularly for herpetic and Acanthamoeba keratitis. Future standardization of the core outcome set in IK-related trials would be invaluable.

Effectiveness and safety of early adjuvant amniotic membrane transplant versus standard antimicrobial treatment for infectious keratitis: a systematic review protocol

OBJECTIVE

The objective of this review is to systematically examine the effectiveness of early adjuvant amniotic membrane transplant versus standard antimicrobial therapy for infectious keratitis.

INTRODUCTION

Infectious keratitis is a major cause of corneal blindness worldwide. Broad-spectrum topical antimicrobial therapy is currently the gold standard for treatment. Amniotic membrane transplant has been employed as an adjuvant therapy to promote corneal healing; however, high-quality evidence is limited.

INCLUSION CRITERIA

This review will consider studies that include patients of all ages with all types of infectious keratitis, including bacterial, fungal, viral, acanthamoeba, mixed, and culture-negative presumed infectious keratitis. The authors will exclude patients who have undergone other types of primary surgery other than amniotic membrane transplant during the initial management and those who had less than seven days' follow-up from the commencement of the treatment.

METHODS

Electronic databases, including MEDLINE, Embase, Cochrane CENTRAL, and relevant registries, will be searched for pertinent studies. Titles, abstract, and full text of the relevant studies will be independently assessed by two reviewers. Extracted data will include authors, year of publication, sample size, types of amniotic membrane transplant techniques, types of causative microorganisms, main outcomes, visual acuity, and adverse events. No restriction will be applied to the date or language. Bibliographies of the included articles will be independently and manually screened by two authors to identify further relevant studies. Eligible studies will be critically appraised by two independent reviewers for methodological quality. A meta-analysis will be performed for the included randomized controlled trials when there are sufficient similarities.

SYSTEMATIC REVIEW REGISTRATION NUMBER

This systematic review has been registered with PROSPERO (CRD42020175593).

Photobiomodulation for non-exudative age-related macular degeneration

BACKGROUND

Age-related macular degeneration (AMD) is one of the leading causes of blindness in high-income countries. The majority of cases of AMD are of the non-exudative type. Experts have proposed photobiomodulation (PBM) therapy as a non-invasive procedure to restore mitochondrial function, upregulate cytoprotective factors and prevent apoptotic cell death in retinal tissue affected by AMD.

OBJECTIVES

To assess the effectiveness and safety of PBM compared to standard care, no treatment or sham treatment for people with non-exudative AMD.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (Issue 5, 2020), Ovid MEDLINE, Embase, ISRCTN, ClinicalTrials.gov and the WHO ICTRP to 11 May 2020 with no language restrictions.

SELECTION CRITERIA

The review included randomised controlled trials (RCTs) on participants receiving any type of PBM therapy for non-exudative AMD compared to standard care, sham treatment or no treatment.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We considered the following outcome measures at 12 months: best-corrected visual acuity (BCVA) ; contrast sensitivity; near vision; low luminance density score; reading speed; vision-related quality of life score; and adverse events such as progression of AMD and conversion to exudative AMD. We graded the certainty of the evidence using GRADE.

MAIN RESULTS

We included two published RCTs from single centres in the UK and Canada, which recruited 60 participants (60 eyes) and 30 participants (46 eyes) respectively. Participants in these trials were people with non-exudative AMD with Age-Related Eye Disease Study (AREDS) categories 2 to 4. One study compared single wavelength PBM with no treatment. This study was at risk of performance bias because the study was not masked, and there was attrition bias. One study compared multi-wavelength PBM with sham treatment and conflicts of interest were reported by study investigators. We also identified three eligible ongoing RCTs from searching the clinical trials database. When comparing PBM with sham treatment or no treatment for non-exudative AMD, there was no evidence of any meaningful clinical difference in BCVA at 12 months (mean difference (MD) 0.02 logMAR, 95% confidence interval (CI) -0.02 to 0.05; 2 RCTs, 90 eyes; low-certainty evidence). One study comparing multi-wavelength PBM with sham treatment showed an improvement in contrast sensitivity at Level E (18 cycles/degree) at 12 months (MD 0.29 LogCS, 95% CI 0.23 to 0.35; 1 RCT, 46 eyes; low-certainty evidence). Visual function and health-related quality of life scores were comparable between single wavelength PBM and no treatment groups at 12 months (VFQ-48 score MD 0.43, 95% CI -0.17 to 1.03; P = 0.16; 1 RCT, 47 eyes; low-certainty evidence). When comparing PBM with sham treatment or no treatment for non-exudative AMD, there was no evidence of any meaningful clinical difference in conversion to exudative AMD (risk ratio (RR) 0.97, 95% CI 0.17 to 5.44; 2 RCTs, 96 eyes; very low-certainty evidence) at 12 months. There was inconclusive evidence that single wavelength PBM prevents the progression of AMD (RR 0.79, 95% CI 0.41 to 1.53; P = 0.48; 1 RCT, 50 eyes; low-certainty evidence). Disease progression was defined as the development of advanced AMD or significant increase in drusen volume. No included study reported near vision, low luminance vision or reading speed outcomes.

AUTHORS' CONCLUSIONS

Currently there remains uncertainty whether PBM treatment is beneficial in slowing progression of non-exudative macular degeneration. There is a need for further well-designed controlled trials assessing dosimetry, powered for both effectiveness and safety outcomes. Consideration should be given to the adoption of agreed clinical outcome measures and patient-based outcome measures for AMD.

The control of conjunctival fibrosis as a paradigm for the prevention of ocular fibrosis-related blindness. "Fibrosis has many friends"

The processes involved in ocular fibrosis after disease or ocular tissue injury, including surgery play an important part in the development or failure of treatment of most blinding diseases. Ocular fibrosis is one of the biggest areas of unmet need in ophthalmology. Effective anti-scarring therapies could potentially revolutionise the management of many diseases like glaucoma worldwide. The response of a quiescent or activated conjunctiva to glaucoma surgery and aqueous flow with different stimulatory components and the response to different interventions and future therapeutics is a paradigm for scarring prevention in other parts of the eye and orbit. Evolution in our understanding of molecular and cellular mechanisms in ocular fibrosis is leading to the introduction of new and re-purposed therapeutic agents, targeting a wide range of key processes. This review provides current and futures perspectives on different approaches to conjunctival fibrosis following glaucoma surgery and highlights the challenges faced in implementing these therapies with maximal effect and minimal side effects.

Effectiveness of adjuvant photoactivated chromophore corneal collagen cross-linking versus standard antimicrobial treatment for infectious keratitis: a systematic review protocol

OBJECTIVE

The objective of this review is to systematically examine the effectiveness of adjuvant photoactivated chromophore for keratitis - corneal collagen cross-linking (PACK-CXL) versus standard antimicrobial treatment alone for corneal healing in patients with infectious keratitis.

INTRODUCTION

Infectious keratitis is a major cause for corneal blindness globally. Broad-spectrum antimicrobial therapy is currently the standard treatment, but there is a growing need for alternative or adjuvant antimicrobial treatment, due to the emerging antimicrobial resistance, long treatment duration and cost of treatment. Photoactivated chromophore for keratitis - corneal collagen cross-linking has been increasingly used as an adjuvant treatment for infectious keratitis but high-quality evidence is limited.

INCLUSION CRITERIA

This review will consider studies that include patients with infectious keratitis, encompassing bacterial, fungal, acanthamoeba, viral, mixed or culture-negative presumed infectious keratitis cases. Patients who have a previous history of infectious keratitis before the study or those that had less than seven days' follow-up from the start of the treatment will be excluded.

METHODS

The electronic databases to be searched will include MEDLINE, Embase and Cochrane Central Register of Controlled Trials. Only English articles will be included. Titles, abstracts and full text of the relevant studies will be assessed by two independent reviewers. The extracted data will include specific details about the study, including authors and study title, year of publication, sample size, populations, and study methods. A meta-analysis will be performed for the included randomized controlled trials when there are sufficient similarities in the reporting of outcome measures.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO CRD42019131290.

Motivators and barriers to engagement with evidence-based practice among medical and dental trainees from the UK and Republic of Ireland: a national survey

OBJECTIVES

To explore the extent to which doctors and dentists in training within the UK and Republic of Ireland (RoI) engage in and with evidence-based practice (EBP), and to identify motivators and barriers to them doing so.

DESIGN

An observational, prepiloted web-based survey developed by a trainee-led focus group.

SETTING

The survey instrument was disseminated to doctors and dentists in training within the UK and RoI during June 2017 via social media and through deaneries, Royal Colleges and specialty-specific mailing lists.

PARTICIPANTS

Data from 243 trainees were analysed; 188 doctors from 31 specialties and 55 dentists from 9 specialties. Responses were received from trainees at all stages of postgraduate training though the overall response rate was low.

PRIMARY AND SECONDARY OUTCOME MEASURES

The motivators and barriers to, and the extent of, trainee engagement with EBP.

RESULTS

Cronbach's α was 0.83. Most trainees (87.6% (n=148) of doctors and 75.1% (n=39) of dentists) consulted the evidence base at least monthly, while 23.1% [n=39 doctors, 12 dentists] of both specialties did so daily. The two most commonly cited barriers to engagement with EBP for both doctors and dentists, respectively, were insufficient time (57.6% (n=95) and 45.1% (n=23)) and a tendency to follow departmental practice (40.6% (n=67) and 45.1% (n=23)). Key motivators for EBP included curiosity, following the example set by senior colleagues and a desire to avoid harm. Most trainees reported high levels of confidence interpreting evidence yet for 26.8% (n=45) of doctors and 36.5% (n=19) of dentists, medical hierarchy would impede them querying a colleague's management plan based on their own reading of the evidence.

CONCLUSIONS

Time, accepted departmental practice and the behaviour of senior clinicians all highly impact on trainee engagement with EBP. Given the low response rate, the extent to which these data represent the overall population is unclear.

Photoactivated chromophore for infectious keratitis - Corneal cross-linking (PACK-CXL): A systematic review and meta-analysis

PURPOSE

To examine the efficacy of adjuvant photoactivated chromophore for infectious keratitis-corneal cross-linking (PACK-CXL) for the treatment of infectious keratitis (IK).

METHODS

Electronic databases, including MEDLINE, EMBASE and Cochrane Central, were searched for articles related to PACK-CXL. All clinical studies, including randomized controlled trials (RCTs), non-randomized controlled studies, case series and case reports, were included. A meta-analysis was further performed when there were sufficient similarities in the included RCTs. Primary outcome measure was time to complete corneal healing and secondary outcome measures included size of epithelial defect and infiltrate, corrected-distance-visual-acuity (CDVA), and adverse events.

RESULTS

Forty-six eligible studies (including four RCTs) with 435 patients were included. When compared to standard antimicrobial treatment (SAT) alone, adjuvant PACK-CXL resulted in shorter mean time to complete corneal healing (-7.44 days; 95% CI, -10.71 to -4.16) and quicker resolution of the infiltrate at 7 days (-5.49 mm²; 95% CI, -7.44 to -3.54) and at 14-30 days (-5.27 mm²; 95% CI, -9.12 to -1.41). There was no significant difference in the size of epithelial defect, CDVA and risk of adverse events. Evidence on the use of PACK-CXL in acanthamoeba and mixed IK was insufficient.

CONCLUSIONS

Our study demonstrates that adjuvant PACK-CXL expedites the healing of IK when compared to SAT alone (low-quality evidence). Further adequately powered, high-quality RCTs are required to fully ascertain the therapeutic effect of PACK-CXL.

Systematic review comparing penetrating keratoplasty and deep anterior lamellar keratoplasty for management of keratoconus

AIM

Perception of reduced incidence of graft rejection after deep anterior lamellar keratoplasty (DALK) has attracted many surgeons towards this technique in keratoconus. This review aims to compare the visual, refractive and graft outcomes after penetrating keratoplasty (PK) and DALK for keratoconus.

METHODS

Electronic searches of PubMed, MEDLINE, EMBASE, Latin American and Caribbean Health Sciences Literature database (LILACS), metaRegister of Controlled Trials (mRCT), ClinicalTrial.gov and the WHO International Clinical Trials Registry Platform (ICTRP) were performed. We included randomized control trials (RCTs) and comparative studies to assess primary and secondary outcomes after PK and DALK in eyes with keratoconus. Primary outcome was best-corrected visual acuity (BCVA) LogMAR at ≥6 months. Secondary outcomes included number of patients with BCVA≥0 LogMAR, uncorrected visual acuity (UCVA) LogMAR, spherical equivalent (SE), refractive and keratometric astigmatism, endothelial cell density (ECD) cell/mm², graft rejection and graft survival.

RESULTS

Eighteen studies (including 2 RCTs) compared DALK (965 eyes) and PK (2402 eyes) for keratoconus. There was strong evidence through RCTs suggesting better LogMAR BCVA at ≥6 months and better LogMAR UCVA with PK; reduced refractive astigmatism and rejection with DALK and no difference in SE and keratometric astigmatism. Moreover, there was weak evidence to suggest better BCVA≥0 LogMAR after PK and no difference in ECD between the two techniques.

CONCLUSIONS

Despite the popularity of DALK amongst corneal surgeons for keratoconus, there is a paucity of high quality RCTs. The existing limited evidence confirms reduced rejection and refractive astigmatism with DALK but better visual outcomes with PK. Internationally agreed data sets and follow-up protocol are warranted.

Improving hospital weekend handover: a user-centered, standardised approach

Clinical Handover remains one of the most perilous procedures in medicine (1). Weekend handover has emerged as a key area of concern with high variability in handover processes across hospitals (1,2,4, 5-10). Studying weekend handover processes within medicine at an acute teaching hospital revealed huge variability in documented content and structure. A total of 12 different pro formas were in use by the medical day-team to handover to the weekend team on-call. A Likert-survey of doctors revealed 93% felt the current handover system needed improvement with 71% stating that it did not ensure patient safety (Chi-squared, p-value <0.001, n=32). Semi-structured interviews of doctors identified common themes including "a lack of consistency in approach" "poor standardization" and "high variability". Seeking to address concerns of standardization, a standardized handover pro forma was developed using Royal College of Physician (RCP) guidelines (2), with direct end-user input. Results following implementation revealed a considerable improvement in documented ceiling of care, urgency of task and team member assignment with 100% uptake of the new proforma at both 4-week and 6-month post-implementation analyses. 88% of doctors surveyed perceived that the new proforma improved patient safety (p<0.01, n=25), with 62% highlighting that it allowed doctors to work more efficiently. Results also revealed that 44% felt further improvements were needed and highlighted electronic solutions and handover training as main priorities. Handover briefing was subsequently incorporated into junior doctor induction and education modules delivered, with good feedback. Following collaboration with key stakeholders and with end-user input, integrated electronic handover software was designed and funding secured. The software is currently under final development. Introducing a standardized handover proforma can be an effective initial step in improving weekend handover. Handover education and end-user involvement are key in improving the process. Electronic handover solutions have been shown to significantly increase the quality of handover and are worth considering (9, 10).

13 years of cultured limbal epithelial cell therapy: a review of the outcomes

The cornea is the clear tissue at the front of the eye which enables the transmission of light to the retina for normal vision. The surface of the cornea is composed of an epithelium which is renewed by stem cells located at the periphery of the cornea, a region known as the limbus. These limbal stem cells can become deficient as a result of various diseases of the eye's surface, resulting in the blinding disease of limbal stem cell deficiency. The treatment of this disease is often difficult and complex. In 1997, it was proposed that a small amount of limbal tissue containing limbal stem cells could be culture expanded and then transplanted. Since then various case reports and case series have been reported showing promising results. Here, we review the outcomes of this procedure over the past 13 years with the aim of highlighting the best culture and surgical techniques to date.

Culture conditions for primary human limbal epithelial cells

The cornea at the front of the eye is covered by an epithelium. This epithelium is maintained by stem cells located at the periphery of the cornea, in a region known as the limbus. Because this region harbors the stem cells for the corneal epithelium, the so-called limbal stem cells, its culture provides considerable interest. Limbal epithelial culture is used for two main reasons. The first is to further our understanding of limbal stem-cell biology. The second is for the culture expansion of limbal stem cells for transplantation purposes in patients with limbal stem-cell deficiency. However, considerable variations in the culture methods for limbal epithelium exist. These include culture media, sera used in the culture, use of 3T3 fibroblasts or amniotic membrane or both, the culture of whole pieces of limbal tissue or enzymatically digested tissue, and the use of airlifting.